x²+y²=6xyx²+y²+2xy=8xy ,x²+y²-2xy=4xy(x+y)²=8xy,(x-y)²=4xy∴(x-y)²/(x+y)²=4/8=1/2∵x>y>0∴(x-y)/(x+y)=√2/2如果本题有什么不明白可以追问,如...